1. Field of the Invention
The present invention relates generally to an oven such as a microwave oven, a cooking range or the like and, more particularly, to an oven with a humidity conditioner capable of cooking food by appropriately humidifying or dehumidifying it, i.e., by appropriately regulating the amount of moisture.
2. Description of Related Art
A conventional microwave oven as shown in FIG. 1 is in wide practical use today.
The oven of FIG. 1 has a casing 101 accommodating a turntable 102, on which food 103 is placed for subsequent induction heating. Reference numeral 105 denotes a motor for driving the turntable 102. A magnetron 106, employed as a microwave supply means, effects microwave heating with the use of high-frequency microwaves of, for example, 2,450 MHz. The microwaves emitted from the magnetron 106 are supplied into an oven cavity 104 through a waveguide 107 to heat the food 103. When the magnetron 106 receives high-voltage electric power from a drive unit 108, it oscillates to generate the high-frequency microwaves. Reference numeral 109 denotes a cooling fan for cooling elements that generate heat.
The conventional microwave oven of the above-described construction is designed to cook the food 103 by heating it from inside by induction heating, and is characterized by very easy and quick reheating (warming) and melting of food.
On the other hand, foods have recently undergone drastic changes, and in particular, progress in manufacturing, storing and transporting frozen food and chilled food has promoted the distribution and spread of cooked foods and other similar foods. Therefore, the use of food has been changed for simplicity as represented by the tendency towards the use of cooked food, and the demands for cooking apparatus have been shifted mainly to cooking by reheating.
In such circumstances, the conventional oven was not sufficient for cooking by reheating because of its heating mechanism. That is, there are a variety of cooked foods including oily foods such as fried food and tempura, vegetable foods such as fresh vegetables and boiled vegetables, stewed foods, and steamed foods. It is now hard to reproduce sufficiently the original taste of the food or to cook healthfully while maintaining nutrients only by heating with microwaves, and an oven capable of reheating in a manner which depends on the conditions of the food has been demanded. At the same time, frozen foods are varied in shape and in combinations of food materials, and thawing by a microwave oven tends to cause uneven heating due to difference in the microwave absorbing characteristics of the food. Accordingly, a cooking apparatus having superior thawing performance has been demanded.
FIG. 2 depicts a conventional combination oven. In high-frequency heating, a drive unit (not shown) supplies a high-frequency oscillator 106 with high-voltage electric power to cause it to oscillate and generate high-frequency microwaves. The high-frequency microwaves generated by the high-frequency oscillator 106 are supplied into the oven cavity 104 through a waveguide 107 to heat food 103 on the turntable 102. During heating, heat generated by a heater 110 is used to heat the food 103 by infrared radiation or convection.
In the above-described construction, however, when cooked rice is reheated, for example, as the food is heated, moisture in the food is vaporized, and the food surface is dried and hardened.
To remedy such a defect, a combination oven with a steam generator as shown in FIG. 3 has been proposed. The oven of FIG. 3 is provided with a steam generator 112 comprised of a water tank 113 and a heater 111, in addition to the construction of FIG. 2.
Food 103 placed on the turntable 102 inside the oven cavity 104 is heated by high-frequency microwaves that are generated by the high-frequency oscillator 106 and introduced into the oven cavity 104 through the waveguide 107. Moreover, the water in the steam generator 112 is converted, by the heater 111, into steam 114, which is introduced into the oven cavity 104 to prevent the food 103 from being dried during cooking.
On the other hand, when fried food is reheated, the water content on the food surface is increased due to migration of moisture onto the food surface caused by vaporization of moisture inside the food, and also due to a reduction in speed of vaporizing from the food surface caused by humidity elevation in the oven cavity.
In this construction, however, since the steam generator 112 comprised of the heater 111 and the water tank 113 is separately provided, water feed into the steam generator 112 and treatment of drain water are troublesome.
Furthermore, when the fried food is reheated, the food surface becomes damp due to an increase of moisture on the food surface in the heating process, and a crisp and fresh surface cannot be expected.